I scanned the last couple months of their blog posts and could not find anything to support that claim. The docs or pricing page don’t seem to indicate anything like that either.

The only related thing I found was that free accounts are limited to one user that can trigger deploys in private repos, while anyone can trigger deploys in public repos (assuming I understood the announcement correctly).

Most people got confused with the wording in their recent policy change for the free plan.

They recently changed the policy for Organization-owned repos. The continuous deployment for organization-owned private repos is no longer allowed in the free plan.

But personal account's public and private repos are still part of the free plan.